The present invention relates to a constant velocity joint having a fixing construction wherein a bellows-like resin boot is fixed at boot attaching portions by boot bands.
Constant velocity joints have a boot mounted thereon in order to prevent leakage of grease sealed in the joint and entry of foreign matter into the joint. Such boot is clamped and fixed at a boot attaching portion of an outer joint member and at a boot attaching portion of a shaft portion of the constant velocity joint by boot bands, respectively. As for such constant velocity joint boots, rubber boots made of rubber, such as chloroprene rubber (CR), and resin boots made of resin material are in common use. In recent years, however, there has been a tendency for resin boots to be used more frequently from the viewpoint of rotational expansion resistance and durability.
FIG. 14 shows a constant velocity joint 11 having a conventional bellows-like resin boot 12 mounted thereon. The resin boot 12 has cylindrical boot fixing portions 12a and 12b on the larger and smaller diameter sides with a bellows portion 12c disposed therebetween. The boot fixing portion 12a on the larger diameter side is clamped and fixed at a boot attaching portion of an outer joint member 11a by a boot band 13 and the boot fixing portion 12b on the smaller diameter side is clamped and fixed at a boot attaching portion of a shaft portion lie by a boot band 14.
A resin boot, as compared with a rubber boot, has a high hardness, lacking in elasticity; therefore, in order to secure a sufficient fixing strength and sealability it is common practice to use, as boot bands, crimp type bands (omega bands) 13 and 14 having clamp portions of omega (.OMEGA.) shape which provide a greater clamping force. The reason why the omega bands have been used for the conventional resin boots is that such a boot band as so-called lever type boot band (a band of the type adapted to clamp by folding back a lever member), which is conventionally used for rubber boots, has failed to provide a sufficient clamping force if they used with the conventional resin boots.
The omega bands 13 and 14, as compared with the lever type boot band and the like, is capable of providing a large clamping force. On the other hand, it has disadvantages in design; for example, since it has a form in which a clamp portion projects radially outward, its maximum radius of rotation is so large as to require a large space to avoid interference with the peripheral parts. Further, since the clamp portion is projecting, its chance of encountering foreign substances (such as flying stones) increases. Further, the band itself is complicated in shape, and requires a greater wall thickness and a greater width than those of boot bands used for rubber boots; thus, it is disadvantageous also from the viewpoint of cost. On the other hand, some of the boot bands have no projecting clamp portion, however, if they are applied to resin boots, it has been difficult to secure a sufficient fixing strength and sealability.